package com.jared.core.test; import com.jared.core.model.People; import java.util.concurrent.ConcurrentHashMap; public class TestCurrentHashMap { public static void main(String[] args) { ConcurrentHashMap map = new ConcurrentHashMap(); People p1 = new People(); p1.setId(1); People p2 = new People(); p2.setId(2); People p3 = new People(); p3.setId(3); map.putIfAbsent("1", p1); map.putIfAbsent("2", p2); map.putIfAbsent("1",p3); map.put("3","1"); } }